text: is an acid gas, and, therefore, the typical sorbent slurries or other materials used to remove the  from the flue gases are alkaline. The reaction taking place in wet scrubbing using a  (limestone) slurry produces calcium sulfite () and may be expressed in the simplified dry form as:
  When wet scrubbing with a  (hydrated lime) slurry, the reaction also produces  (calcium sulfite) and may be expressed in the simplified dry form as:
  When wet scrubbing with a  (magnesium hydroxide) slurry, the reaction produces  (magnesium sulfite) and may be expressed in the simplified dry form as:
  To partially offset the cost of the FGD installation, some designs, particularly dry sorbent injection systems, further oxidize the  (calcium sulfite) to produce marketable  (gypsum) that can be of high enough quality to use in wallboard and other products. The process by which this synthetic gypsum is created is also known as forced oxidation:
  A natural alkaline usable to absorb  is seawater. The  is absorbed in the water, and when oxygen is added reacts to form sulfate ions  and free . The surplus of  is offset by the carbonates in seawater pushing the carbonate equilibrium to release  gas:
  In industry caustic soda () is often used to scrub , producing sodium sulfite: